The present invention relates to a vehicle speed control adaptive cruise control and vehicle to vehicle distance control device.
Japanese Patent Laid-open Nos. 9-263160 and 2001-30797 disclose a vehicle speed control device. This control device provides, if it becomes unable to detect a forward vehicle, a constant speed control for a predetermined period of time, during which a speed in accordance with a headway distance immediately before the event is maintained, and thereafter restricts gradual acceleration or prevents a shift from a following control (headway distance automatic control) to the constant speed control.
Such a vehicle speed control device, however, shifts from the adaptive cruise control (vehicle to vehicle distance control) mode to the constant speed control mode without clearly identifying a driver""s intention. This gives the driver a sense of a timing lag and awkwardness. It could also give the driver, in a variety of occasions, a sense of uneasiness because of a vehicle being accelerated at timings not exactly the driver expects.
The present invention provides a device that performs, if it becomes unable to detect a forward vehicle, the constant speed control using an actual vehicle speed or a corrected vehicle speed of a subject vehicle immediately before the event and refrains from shifting to the constant speed control using a set vehicle speed preset by the driver until the driver depresses an accelerator pedal.
The invention can prevent the vehicle from being accelerated unexpectedly.